Unison general secretary Dave Prentis said: "This list fails to shame the larger care firms who are equally guilty of denying staff a fair wage. Those in the spotlight today are just the tip of the iceberg.

"HM Revenue & Customs needs to get much tougher with more inspections to identify scrooge employers."

Unite assistant general secretary Steve Turner said: "The Government needs to crack down further on employers who failed to pay the national minimum wage to some of the most low-paid and vulnerable workers in the country.

"The fact that the Government has mounted only 13 prosecutions for non-compliance since 2007 is pathetic.

"In America, bad bosses are jailed and heavily fined for 'wage theft' which is what this is, exploiting workers in such a shameful fashion."